Diagnostic membrane containing fatty acid sarcosinate surfactant for testing oral fluid

Abstract

A diagnostic test strip for determining the presence of a specified analyte in a fluid sample is described. The test strip has a test membrane sandwiched between two layers of a plastic sheath. The upper layer of the sheath has a sample well into which a liquid sample is placed. The test membrane has a sample receiving zone typically containing a buffer and a fatty acid sarcosinate. Adjacent to the sample receiving zone is a reagent zone containing reagent chemicals including gold colloid particles coated with antibodies to the specified analyte. In fluid connection with the reagent zone is a test zone containing immobilized molecules of the specified analyte. Preferably, in fluid connection with the test zone is a control zone containing an indicator that changes color when wetted by the sample and a liquid sink zone to absorb excess liquid in the sample.

We claim:  
     
       1. A diagnostic test strip comprising a bibulous matrix having: 
       a sample receiving zone for receiving a liquid specimen of oral fluid suspected of containing a particular analyte,  
       reagent chemistry located for contact with the sample for detecting the particular analyte, and  
       spaced from the sample receiving zone in a sample migration direction a detection zone for determining the presence of said particular analyte by providing a detectable change observable in the detection zone,  
       wherein the sample migrates between the sample receiving zone and the detection zone, and  
       wherein the sample receiving zone contains a sodium myristol sarcosinate surfactant.  
     
     
       2. The diagnostic test strip according to claim  1 , wherein the bibulous material comprises a microporous membrane. 
     
     
       3. The diagnostic test strip according to claim  1 , wherein the reagent chemistry includes antibodies to said particular analyte that are freely mobile when the test strip is moist, and the detection zone contains immobilized molecules of said particular analyte that are not free to move when the test strip is moist. 
     
     
       4. The diagnostic test strip according to claim  1 , further comprising a control zone downstream of the detection zone, wherein the presence of the sample causes a detectable change. 
     
     
       5. The diagnostic test strip according to claim  1 , further comprising a liquid sink zone to absorb excess sample. 
     
     
       6. The diagnostic test strip according to claim  1 , further comprising a liquid sink zone at an opposite end of the diagnostic test membrane from the sample receiving zone. 
     
     
       7. The diagnostic test strip according to claim  1 , wherein the bibulous material comprises as separate components, each of which is in fluid contact with each other, a sample receiving zone, a reagent chemistry zone, and a detection zone. 
     
     
       8. The diagnostic test strip according to claim  7 , wherein the bibulous material further comprises a separate liquid sink zone. 
     
     
       9. The diagnostic test strip according to claim  7 , wherein the bibulous material further comprises a separate control zone. 
     
     
       10. The diagnostic test strip according to claim  7 , wherein the bibulous material comprises an open cell, polyurethane foam membrane that is heat and pressure treated to provide at least one surface that can absorb fluid more readily than untreated polyurethane foam. 
     
     
       11. The diagnostic test strip of claim  1 , wherein the oral fluid comprises saliva.